Advanced Materials Research Vols. 126-128

Abstract: This study investigated adhesion of coatings on a grinding surface. This was carried out using scratch testing as a function of surface roughness. Three types of coatings were explored: TiAlN, CrSiN and TiSiN. With smaller surface roughness, the coating adhesion showed a tendency to become stronger. In particular, in the case of surface roughness under 2 micrometers for a coating, the coating adhesion was good. Specifically, the CrSiN coating yielded a very smooth surface.

Abstract: The application of advanced ceramics in high-tech industries is increasing considerably due to their superior properties. However the difficulties involved and manufacturing costs have been impediments to the widespread replacement of metals by the advanced ceramics. One of the main targets in grinding of these materials is increasing the machining efficiency while preserving the surface integrity. Hence in order to reduce the grinding forces and temperatures and increase the material removal rate, a specially designed segmented wheel (T-Tool) has been developed. Reducing the static cutting edges via segmenting the wheel which automatically leads to reduction of momentarily engaging cutting edges results in a reduction of rubbing and plowing regimes and therefore a decrease in the specific grinding energy. The obtained results show that the application of the T-Tool wheel can increase the G-ratio and decrease the grinding forces considerably. A decrease of up to 35% of grinding forces has been achieved.

Abstract: Brazing experiments of polycrystalline CBN abrasive grains and AISI 1045 steel matrix using 95(72Ag-28Cu)-5Ti (wt.%) filler alloy were carried out at the heating temperature of 900 °C for the dwell time of 8 min. The microstructure of the brazing interface among PCBN grain, Ag-Cu-Ti alloy and steel matrix, was characterized with optical microscope, scanning electron microscope and X-ray diffraction equipment. Grinding performance of the brazed polycrystalline CBN abrasive tools was evaluated experimentally by comparison with monocrystalline CBN counterparts. The results show that the reaction layer between polycrystalline CBN abrasive grain and Ag-Cu-Ti filler layer consists of the compounds of Ti-nitride, Ti-borides and Ti3AlN. The resultants have played an important role in terms of strong chemical joining at the grain-filler interface. The brazed abrasive tools with polycrystalline CBN grains have given higher material removal rate and longer service life than that with monocrystalline CBN ones.

Abstract: Under optimum grinding conditions, a constant grinding force is exerted on a workpiece during ductile-mode grinding of BK7 glass. Based on the results, the cutting force, specific grinding energy, and depth of cut for a single grain were calculated. It was found that a single grain was easily removed from the material. However, grinding is impossible because surface burning occurs on the workpiece. In order to avoid burning, a single-crystal silicon wafer (1,0,0) surface was ground with thrust force directional vibration-assisted grinding. The normal grinding force with vibration was comparatively low, but was quite stable. The removal rate was approximately three times greater than that without vibration. The results indicate that the successive abrasive grains of the grinding wheel remove the material intermittently.

Abstract: The in-process sharpening mechanism of the grinder during the grinding process of a CVD diamond film surface is investigated using the composite electro-plating in-process sharpening (CEPIS) technique. The bath concentration is employed to investigate the variation of coating structure deposited on the grinder. Results show that the land area ratio increases with increasing nickel chloride concentrations (NiCl2．6H2O) of the plating bath from 10 to 30 g/L, and the coating structure becomes very smooth without porous area at the nickel chloride concentration of 75 g/L. Therefore the coating structure becomes compact to hold the diamond particles rigidly. Consequently, the grinding ability of the grinder can be significantly improved, where the mirror-like surface of the CVD diamond film can be achieved.

Abstract: Electrically conductive polycrystalline composite diamond (EC-PCD) material, which consists of electrically conductive diamond grits, has recently been developed for the purpose of providing the material with both excellent tool property and machinability. This paper deals with the material property and the wear characteristics of EC-PCD. The result shows that the EC-PCD is superior in heat resistance compared with the conventional PCD. And the EC-PCD shows low frictional wear at high temperature in sliding test against stainless steel disk. Furthermore, in a cutting test of aluminum alloy, the EC-PCD cutting tool shows the same wear characteristics as the conventional PCD tool.

Abstract: A new PCD (electrically conductive PCD: EC-PCD) consisting of electrically conductive diamond particles has recently been developed. The authors have proposed a complex grinding assisted with electrical discharge machining (EDM) where discharge machining and grinding are used in combination during material removal to realize high efficiency, low and stable grinding force and low wheel wear for the EC-PCD. In this study, the effect of constant-force grinding in a complex grinding assisted with electrical discharge machining of EC-PCD was investigated. As a result, it was found that higher material removal rate, higher grinding ratio and better surface condition were obtained on EC-PCD compared with standard PCD (S-PCD) in the constant-force grinding.

Abstract: This paper explores the wear mechanisms of a Sialon ceramic tool in ultra high speed turning of Nickel-based alloy Inconel 718. Microstructures of the chips are also investigated. Stereo optical microscope and scanning electron microscope (SEM) are employed to observe worn surfaces of the tool produced by various wear mechanisms and morphological features of chips. In addition, the elemental compositions of wear products are evaluated by energy-dispersive X-ray spectroscopy (EDS). As a result of the study, wear mechanisms identified in the machining tests involve adhesive wear and abrasive wear. At the initial stage of cutting process, crater wear and flank wear are the main wear patterns. At the rapid wear stage, the SEM and EDS results showed that the adhered elements of Inconel 718 alloy on the tool rake face such as Ni, Fe and Cr accelerated the tool wear rate. Meanwhile, it was found that the chip morphology was serrated type under ultra high speed cutting condition, furthermore, the tendency of serration of the chip increased with the increase in cutting speed and feed rate.

Abstract: In this paper, surface topography characteristics of electrochemical mechanical finishing (ECMF) for steel was investigated. The scanning electron microscopy (SEM) was used to observe the surface topography. And the microcosmic geometry parameters were measured by Talysurf SLI2000. Compared with original surface, the surface topography characteristics of the workpiece machined by ECMF have been analyzed with altitude density function (ADF) and auto correlation function (ACF). The results show that there exist periodicity component in surface profile before and after finishing. The auto correlation curves of ECMF surface have a smaller average period compared with grinding surface. The low-frequency component and the mean ripple peak distance of original surface profile are obviously decreased. Furthermore, the ripples and peak density are increased, and the surface roughness Ra is decreased from 0.231μm to 0.023μm. The results indicate that surface quality, material ratio of the profile and wear resistance machined by ECMF are improved obviously.

Abstract: The effects of cutting parameters on the transverse vibration of diamond circular saw blade were experimentally investigated. Transverse vibration was online measured by a novel measuring system developed by wireless sensor. Meanwhile, axial force on saw blade was measured by a dynamometer. By the experimental results under different cutting parameters, the time domain characteristics of transverse vibration of saw blade were analyzed, and the relationships between transverse vibration and cutting parameters were also obtained. Axial deformation is greatly influenced by the axial force acting on saw blade.